sleeve gastrectomy

**Procedure:** Laparoscopic vertical resection of the greater curvature of the stomach, including the fundus and most of the body, leaving a banana-shaped tube (~100–150 mL) along the lesser curvature. No intestinal bypass and no anastomosis; the pylorus and duodenum are preserved, so absorption of nutrients is largely normal. The procedure is irreversible because the resected stomach is removed.

**Mechanism of weight loss:** - Restriction: small gastric volume leads to early satiety. - Hormonal: the fundus is the main site of ghrelin ("hunger hormone") production by gastric X/A-like cells, so resection causes a fall in ghrelin and reduced appetite. Increased GLP-1 and PYY (from faster nutrient delivery to the distal bowel) improve satiety and glycemic control. - Typical excess weight loss is ~60–70%, and it improves T2DM, HTN, OSA, and dyslipidemia, though somewhat less than Roux-en-Y gastric bypass (RYGB).

**Indications (ASMBS/IFSO 2022 update):** BMI ≥35 regardless of comorbidities, or BMI 30–34.9 with metabolic disease. Consider at BMI ≥30 per the updated guidelines (older NIH criteria were BMI ≥40, or ≥35 with comorbidities). Candidates should have failed nonsurgical weight loss and have no uncontrolled psychiatric disease or active substance abuse.

**Complications:** - GERD (worsening or de novo): the most important long-term issue, caused by increased intragastric pressure, loss of the angle of His, and loss of the fundus. Preexisting severe GERD or Barrett's esophagus favors RYGB over sleeve. - Staple-line leak (usually near the gastroesophageal junction): presents with tachycardia, fever, and abdominal pain days after surgery. Diagnose with CT with contrast or an upper GI series. Management: resuscitation, drainage, antibiotics, stenting. - Bleeding along the staple line, stricture or stenosis (often at the incisura angularis), and VTE (use prophylaxis). - Nutritional deficiencies: less than with RYGB or biliopancreatic diversion since there is no bypass, but intrinsic factor is reduced, so B12 deficiency can occur. Also monitor iron, folate, vitamin D, and calcium. Lifelong supplementation is recommended. - Dumping syndrome: much less common than with RYGB because the pylorus is preserved. - Weight regain over the long term, and sleeve dilation.

**Comparison of procedures (high-yield):** - Sleeve gastrectomy: restrictive, plus hormonal effects. No malabsorption, and the stomach remains endoscopically accessible. The risk is GERD. - RYGB: restrictive and mildly malabsorptive. It is the best choice for patients with GERD or severe T2DM. Complications include dumping, marginal ulcer, internal hernia, and iron, B12, and calcium deficiencies. The excluded stomach is hard to access endoscopically. - Adjustable gastric band: purely restrictive, with high rates of reoperation, slippage, and erosion. It is now rarely used. - Biliopancreatic diversion with duodenal switch: the most malabsorptive option, with the most weight loss and the highest risk of nutritional deficiencies (fat-soluble vitamins) and protein malnutrition.

**Boards pearls:** - The fundus is the source of ghrelin, so resecting it reduces hunger. - Postoperative fever, tachycardia, and abdominal pain suggest a leak. Tachycardia is the earliest and most sensitive sign. - Long-term worsening reflux after sleeve is managed by conversion to RYGB. - Dumping is rare after sleeve because the pylorus is intact.